1. Field of the Invention
The present invention relates to an operational display device and a method of controlling the same as well as a recording medium, and particularly to an operational display device capable of changing a direction of a display portion and a method of controlling the same as well as a recording medium.
2. Description of the Related Art
Recently, an electrostatic touch panel has been introduced as a touch panel representing one example of an operation and input device. In design thereof, a frame is narrowed and flat design is adopted, and hardware keys are eliminated as much as possible.
Such a touch panel has become a mainstream of a new operation and input device mainly operated through a touch operation, which is represented by a smartphone or a tablet terminal. In a general tablet terminal, an application for displaying such an image as a photograph or a text document is provided with such control that a display image of interest is always erected when viewed from a user.
In such an operational display device having a function to always have an erected display image displayed to a user, whether or not to activate automatic rotational display on an application level is set. In addition, control as described above is made use of as a function convenient for a user, which allows easy view of erected display as a photograph viewer or in the case where a user views a text document.
For example, Patent Literature 1 (Japanese Laid-Open Patent Publication No. 2010-055511) proposes an apparatus including a display unit for displaying an image on a screen based on image data, a touch panel, and an angle detection unit, in which a displayed image is displayed in a zoomed-in or zoomed-out manner in accordance with an angle of rotation of the display unit onto which a touch operation is being provided, so that the displayed image is always erected when viewed from a user and processing for zoom-in and zoom-out display in a zoom operation and for movement of an object to be focused on is performed quickly in a simplified manner.
Likewise a touch panel provided in an MFP (Multi Function Peripheral) representing one example of a multi function machine having a plurality of functions such as copying or facsimile, in an operation and input device where an operation icon (button) is arranged for setting various functions or making transition to another screen, it is usual to create a display image with display on a horizontally oriented LCD (Liquid Crystal Display) being defined as the reference.
In the case of a (movable) operational display device in which a direction of a display device can be changed to a vertically oriented direction or in the case of a portable removable operational display device, the following problems which have not occurred in a fixed display device arise.
For example, such a rotational display function that an image is always erected when viewed from a user is available as one of display functions. If a display device has such a rotational display function, a (horizontally oriented) display image designed with display on a horizontally oriented LCD being defined as the reference is displayed in a zoomed-out manner in its entirety in accordance with a width dimension of LCD display when the display device is rotated and held in a vertically oriented direction. Therefore, since characters, photographs, and the like are displayed with a small size, visibility becomes poor.
It may be possible to solve this problem by realizing zoom-in display at prescribed magnification through a zoom-in display operation key input such as an operation of a touch panel icon, however, it may be difficult to realize zoom-in display with an intended portion being focused on. Therefore, there has been a case where only zoom-in display can be realized with a display center of rendering at the same magnification being defined as the reference.
With a touch panel adapted to multiple touch operations, an operation for zoom-in display with focus being placed on any area can be performed by performing a pinching operation. Whether or not a user can realize zoom-in display of his/her intended whole area, however, is dependent on setting of fixed magnification in a zoom-in operation. Therefore, there may also be a case where an area in which zoom was intended may not be included in a zoomed-in screen.
Furthermore, it is also possible that a user's operational procedure increases and an operation becomes troublesome. For example, each time a direction of holding of a display device is rotated, the user has to perform a zoom-in operation.
In addition, with the conventional operation and input device disclosed in Patent Literature 1 described above, though an operation for zoom-in display in a zoom operation and for movement of an object to be focused on can quickly be performed, a touch operation for selecting an area of interest is necessary and such a method is not necessarily an easy-to-use operation method. In particular, in realizing a display function to rotate a display image by 90 degrees for display such that the image erects from a viewpoint of a user when a direction of holding of an operational display device is rotated by 90 degrees, the user has to perform an operation to change a direction of holding while he/she performs a touch operation of an area of interest, which makes an operation extremely difficult.
The present invention was made in view of such circumstances and an object thereof is to improve visibility of a part of an image displayed on a display screen without a troublesome operation in an operational display device.